Aortic Aneurysms and Dissections Series

Abstract

The aortic wall is composed of highly dynamic cell populations and extracellular matrix. In response to changes in the biomechanical environment, aortic cells and extracellular matrix modulate their structure and functions to increase aortic wall strength and meet the hemodynamic demand. Compromise in the structural and functional integrity of aortic components leads to aortic degeneration, biomechanical failure, and the development of aortic aneurysms and dissections (AAD). A better understanding of the molecular pathogenesis of AAD will facilitate the development of effective medications to treat these conditions. Here, we summarize recent findings on AAD published in ATVB. In this issue, we focus on the dynamics of aortic cells and extracellular matrix in AAD; in the next issue, we will focus on the role of signaling pathways in AAD.

Keywords: aortic aneurysm; extracellular matrix; inflammation; muscles; proteoglycans.

Figure 1.. Aortic aneurysms and dissections.

(A) Aortic aneurysm occurs when the progressive weakening of the aortic wall causes the aorta to enlarge. (B) Aortic dissection occurs when a tear forms within the aortic wall and causes blood to flow between the laminal layers of the media, thereby creating a false lumen. Used with permission.

Figure 1.. Aortic aneurysms and dissections.

(A) Aortic aneurysm occurs when the progressive weakening of the aortic wall causes the aorta to enlarge. (B) Aortic dissection occurs when a tear forms within the aortic wall and causes blood to flow between the laminal layers of the media, thereby creating a false lumen. Used with permission.

Figure 2.. Elastin-contractile unit.

(A) The lamellar unit is composed of smooth muscle cells (SMCs) sandwiched between two layers of elastic fibers and surrounded by collagen bundles. (B) The elastin-contractile unit is a unique configuration of elastin fibers, focal adhesions/dense plaques in the SMC plasma membrane, and contractile filaments inside the SMCs. Used with permission.

Figure 2.. Elastin-contractile unit.

(A) The lamellar unit is composed of smooth muscle cells (SMCs) sandwiched between two layers of elastic fibers and surrounded by collagen bundles. (B) The elastin-contractile unit is a unique configuration of elastin fibers, focal adhesions/dense plaques in the SMC plasma membrane, and contractile filaments inside the SMCs. Used with permission.

Figure 3.. Proteoglycan metabolism in the aortic wall.

(A) Illustration of normal aortic wall with intact proteoglycans (PG), such as aggrecans, attached to hyaluronan (HA) and healthy smooth muscle cells (SMC). (B) Illustration of degenerative aortic wall with accumulated proteoglycan (e.g., aggrecan) fragments, elastin fiber fragmentation, and SMC death.

Figure 3.. Proteoglycan metabolism in the aortic wall.

(A) Illustration of normal aortic wall with intact proteoglycans (PG), such as aggrecans, attached to hyaluronan (HA) and healthy smooth muscle cells (SMC). (B) Illustration of degenerative aortic wall with accumulated proteoglycan (e.g., aggrecan) fragments, elastin fiber fragmentation, and SMC death.